Up to now, an air conditioning function of a seat has been required to quickly cool down or to quickly warm up and a uniform thermal sensation without temperature bias. In response to such a requirement, a seat air conditioner that has been proposed which is capable of switching between a mode for blowing out the air whose temperature has been adjusted by an air conditioning unit from a seating surface of a seat and a mode for blowing out the vehicle interior air from the seating surface of the seat (for example, refer to Patent Literature 1).